This invention relates to apparatus for measuring fluid flow. More particularly, this invention relates to apparatus providing an accurate digital representation of fluid flow velocity.
It is well known in the art to determine the flow velocity of a fluid, for example, the flow rate of oil in a pipeline, by inserting an obstruction such as an orifice plate in the flow stream of the conduit and to measure the pressure differential between the upstream and downstream sides of the obstructing orifice plate. As is well known, the magnitude of this pressure differential is related to the rate of flow of the fluid by a square law function, that is, the measured differential pressure is, for most practical purposes, directly related to the square of the fluid velocity.
A major deficiency in presently utilized fluid flow rate measurement devices is that they are essentially analog devices. Due to both their mechanical complexity and due to the hysteresis of the diaphragms utilized, these devices do not provide the degree of accuracy that is frequently desired. Further, the determination of total flow over a period of time, which may be required, for example, in applications where it is desired to mix various fluids in predetermined quantities, requires mechanical linkages of a complexity which serves both to decrease accuracy and to increase the likelihood of device failure.